The collection consists of six series: series 1, General Correspondence; series 2, letters from and relating to Dónall Mac Amhlaigh; series 3, typescripts and other papers relating to Dónall Mac Amhlaigh; series 4, organization and business papers; series 5, essays, notes and literary manuscripts; series 6, family papers.

Series 1, letters to Pádraig Ó Concheanainn or to members of An Clóchomhar, includes a number of personal letters, but the majority of the letters are of a business nature, concerning the publications of An Clóchomhar.

Series 2 and 3 concern Dónall Mac Amhlaigh. The earliest letters concern the projected publication of a book containing Mac Amhlaigh's stories based on his diary of an Irish laborer in England, and they also discuss other works and the translation to English of Dialann Deoraí. The letters span a period of thirteen years and in addition to discussing Mac Amhlaigh's writing and publishing, they include anecdotes about his family and himself.

Papers in Series 4 concern the business of Irish language and publishing organizations, and Series 5 consists of an assortment of drafts, typescripts and literary manuscripts by various authors. Within this collection are a some papers of or concerning Tomás Bán, and these have been placed, when identified, in Series 6 along with other papers of the Ó Concheanainn family.

An Clóchomhar was founded in 1954 initially as a printing and publishing cooperative to produce Irish language Christmas cards. By 1958 it had a book publishing committee, "Coiste na Leabhar" which became the most prominent aspect of An Clóchomhar. It became the foremost publisher of academic books in the Irish language. Connemara publisher Cló Iar-Chonnacht now owns the stock and rights of An Clóchomhar. Most of the correspondence in this collection, along with the papers in Series 4, are related to the work of An Clóchomhar.

A letter of complaint regarding the constant tardiness of the person preparing the radio news.

Letters written to Seosamh Ó hÓgartaigh and to Seosamh Ó Duibhginn.